The present invention relates to cutter tools for trimming liners that are inserted into a cylinder bore.
It is desirable to provide sleeve-type inserts (sometimes called xe2x80x9clinersxe2x80x9d) made of optimal materials and shaped for friction-fit into cylinder bores of cylinder blocks of internal combustion engines. By using inserts, the cylinder blocks can be made of optimal materials (e.g. low-cost materials that are easily machinable and have high heat transfer properties), and yet the cylinder bores can also be made of optimal materials that will last a long time (e.g. higher cost materials having longer wear and better bearing properties). It is further desirable to minimize the cost of installation of such sleeve-type inserts. For example, most sleeve-type inserts that are friction- or interference-fit into position have a protruding end that must be trimmed after installation. It is desirable to provide an installation and trimming operation that can be done without the need for an expensive milling machine for trimming. This applies to original equipment manufacturers, such as large automotive companies, and also applies to job shops and smaller companies, such as re-manufacturers and engine rebuilders. A problem is that it is difficult to control quality when trying to accomplish machining and trimming operations via manually-operated methods. Fixtures can help, but they are often expensive to build and maintain. Further, they are often cumbersome to use and it is often non-intuitive or unclear how to set up and use them.
Another problem with trimming inserts is that the trimmed chips can fall into the cylinder bore. If not removed, they can score and damage the cylinder wall surface, causing considerable damage and thus requiring a second major engine overhaul. Small chips can be especially problematic, since they wedge between the piston and the cylinder wall, where they are engaged and are scraped back and forth with the piston rings. However, removal of all chips is tedious and difficult, especially when the engine block is still in the vehicle where lighting is poor and access is difficult.
Yet another problem with trimmed inserts is their top surface, which must be trimmed flush with a top surface of the cylinder block, so that the head gasket can seal properly between the cylinder block and the cylinder head to prevent oil and radiator fluid cross-contamination and leakage to the cylinder bores. It has been found that the cutters on milling machines, which cutters are rotated as they move linearly across a cutting area, leave a non-cylindrical crisscross pattern on the top surface of the trimmed inserts. This crisscross pattern includes small grooves that lead from the inner surface of the insert (i.e. the cylinder bore) to the outer surface of the insert (i.e. to the top surface of the cylinder block). These small grooves form passages that allow pressurized exhaust gases to sneak under the gasket and over the top of the insert to a remote location adjacent the gasket. Over time, the exhaust gases can enlarge the small grooves, causing premature failure of the gasket, premature loss of compression and engine failure, and other problems. It is desirable to provide an insert trimming apparatus that does not leave a crisscross pattern of grooves on the trimmed end of a cylinder bore insert, to improve the ability to seal a trimmed end of the insert.
Accordingly, a trimming apparatus is desired solving the aforementioned problems and having the aforementioned advantages.
In one aspect of the present invention, a trimming apparatus for trimming a newly-installed sleeve liner after the liner is positioned in a cylinder bore of a combustion engine component includes a trimming tool adapted to shave off a protruding end of the newly-installed sleeve liner, and a tool holder. The tool holder has a first section shaped and adapted to stably engage the combustion engine component, and a second section operably supporting the trimming tool for rotation over the selected cylinder bore when the tool holder is attached to the combustion engine component. A tie-down device is shaped to secure the tool holder to the engine component.
In another aspect of the present invention, a trimming apparatus includes a trimming tool adapted to shave off a protruding end of the newly-installed sleeve liner, where the trimming tool has a drive shaft and has an enlarged cutter head connected to the drive shaft and further has a stop. A tool holder has a bore neck operably supporting the drive shaft of the trimming tool for rotation and for limited longitudinal movement, with the longitudinal movement being limited by engagement of the stop against the tool holder in at least one direction. The tool holder further has an enlarged pocket for receiving the cutter head and for positioning the cutter head adjacent a protruding end of the newly-installed sleeve liner when the tool holder is supported on the combustion engine component. The tool holder is configured and sized for manual manipulation and operation and has an end shaped and adapted to stably engage the combustion engine component while the trimming tool is being operated manually.
In another aspect of the present invention, a method includes steps of providing a combustion engine component with a damaged cylinder bore, and friction-fitting a sleeve liner of bearing material in the damaged cylinder bore to repair the cylinder bore. The method further includes providing a trimming tool having a cutter adapted to shave off a protruding end of the newly-installed sleeve liner, the cutter being rotatable about a centerline that is adapted to be positioned collinearly with a centerline of the cylinder bore. The method includes attaching the trimming tool to the combustion engine component including holding the trimming tool for rotation over the selected cylinder bore with the centerline of the cutter aligned with the centerline of the cylinder bore; and rotating the trimming tool to trim a protruding end of the liner.
These and other aspects, objects, and features of the present invention will be understood and appreciated by those skilled in the art upon studying the following specification, claims, and appended drawings.